Means and method of tube drawing



W. J. DENNIS MEANS AND METHOD 0F TUBE DRAWING Sqn. 19, 1939.

-Fled Jan. 28, 1937 @D mw] Patented Sept. 19,v i939 PATENT oFFlCE v 2,173,099 l y MEANS AND METHOD or TUBE DRAWING Walter J. Dennis, Chicago, Ill., assignor to Vascoloy-Ramet Corporation, North Chicago, Ill., a corporation of Delaware Application January 28, 1937, Serial N0 122,854

Y 11A Claims.

This invention relates generally to means and methods of tube drawing and more particularly to air cooled tube drawing mechanism.

It is conventional practice in drawing tubes to reduce the diameter thereof to move the Itube between the outer peripheralsurface of a mandrel and the inner annular surface of a die. When hard metals which hard metals are characterized by lower coeiiicients of expansion and thermal conductivity than the ferrous metals commonly used in this and similar applications, such as tungsten carbide, tantalum carbide and the like, are employed in tube drawing, considerable heat is developed and, unless this heat is properly dissipated, breakage of parts may result. In fact, one of the most serious diiiiculties heretofore experienced in the use of hard metal of the aforesaid type for tube drawing has been the tendency of such metal to break due to the heat developed by the frictional engagement of the tube with the hardmetal. It has sometimes been the practice to mount a bushing of hard metal on a core of metal having a greater coelicient ofexpansion than the hard metal with the result that the heat generated by the friction of the drawingl operation causes the core to expand with the. resultant breaking of the bushing. This will .be morev yreadily appreciated when itis understood .that the core must snugly lit the hard'metal bushing in order to lend the required support for the bushing when it is subjected to great pressure during the drawing op. eration.

It is one of the important objects of the present invention to provide means whereby a tube may be drawn over a hard metal bushing without the inherent danger of breakage resulting from heat and to this end the invention contemplates a mandrel construction whereby heat generated by friction of the drawing operation may be rapidly dissipated.

More specifically the present invention contemplates tube drawing, mechanism including a mandrel adapted to support a hard metal bushing, said mandrel being so constructed and arranged as to enablernovement of air into contact with said bushing whereby to carry off excessive heat and thus maintain operating temperatures within predetermined limits.

Still more .speciiically the invention contemplates a mandrel which will not only snugly and securely receive and support a hard metal drawing bushing, but will enable air to be carried into direct contact with the inner periphery of the bushing in such a mannerv as to eectvely dissip'ate excessive heat from the bushing and from the vicinity thereof.

The foregoing and numerous other objects and advantages will be more apparent from the following detailed description, when considered in connection with the. accompanying drawing, wherein- Figure 1 is a central sectional view of tube drawing mechanism whereby the method of drawing contemplated by the presen-t invention may be emciently practiced;

Figure 2 is a transverse sectional view taken substantially along the line 2-2 of Figure 1;

Figure 3 is a fragmentary longitudinal sectional view similar to Figure 1, disclosing a modiiied form of mandrel; and

Figure 4 discloses still another modified mandrel construction.

Referring now to the drawing more in detail wherein like numerals have been employed to designate similar parts throughout` the various gures, it will be seen that one embodiment of the present invention, whereby the improved method of tube drawing may be practiced, in-

cludes a drawing die indicated generally by the numeral I0, and this die includes a suitable hard metal drawing die proper I2 mounted within a holder I4. The die proper I2 isvpreferably made of hard metal, such as a'hard metal alloy now obtainable on the open market, as, for example, tungsten carbide, tantalum carbide and the like. The inner diameter of the die I2 determines the externaldiameter of a metallic tube, such as the vtube I6. The entering side of the die I2 is suitably chamfered or beveled at I8 to facilitate the drawing ofthe tube I6 therethrough. f

Disposed in co-axial and cooperative relation lwith the die I2 is a die or die bushing 20 which is associated with and supported by a mandrel designated generally by the numeral 22. In Figure 1 this mandrel includes an inner core member 24 which is centrally disposed and threaded within a mandrel sleeve 26. The outer extremity of the core member 24 is provided with a head 28 designed to clampingly engage the outer end surface'of the die bushing 20 when the core is tightened within the mandrel sleeve 26.

The die bushing 20 is snuglypsupported upon the peripheral surface of a reduced core section 30 ofthe core member 24. The core member 24, which is in turn rigidly supported within the sleeve 26, provides a very rigid, rm support for the die bushing in order that said bushing may withstand the severe pressure conditions develpped during the drawing operation. By tightening the core member 24 within the sleeve member 26 the bushing is rmly clamped between the head 28 and a shoulder 32, as clearly shown in Figure l.

The sleeve 26 is carried by a mandrel member 34, said sleeve being internally threaded to be received by a threaded reduced mandrel sec-` Particular attention is directed to the' tion 36. internal passages throughl which air may be directed for the purpose of cooling the die bushing 20 during the tube drawing operation. Beginning at the left extremity of Figure l, it will be noted that passages 38 adaptedto be connected to any suitable air pressure means or pump (not shown) merge with a central passage 40 in the mandrel section 36. This central passage 40 communicates with a central passage 42 provided within the core member 24, and the right extremity of this passage 62 communicates with radially inclined passages M, each of said passages 44 communicating with a companion pas'- sage 46. These passages 136 extend longitudinally and permit air to be carried into direct contact with the internal periphery of the die bushing 20. The leit extremities of these passages i6 communicate with companion radial or discharge passages d8. A threaded plug closes the outer extremities of the inclined radial passages ifi and facilitates the machining of the longitudinal passage 42.

From the foregoing, it will be apparent that air which is introduced at the left end of the mandrel, passes to the right extremity thereof and then outwardly and in a reverse direction along the inner periphery of the die bushing 20 and thence outwardly through the radial passages or ports 18. This expansion of air from one passage or chamber to another and the continued movement thereof is suicient to carry away excess heat generated by the friction of the tube drawing operation and positively precludes overheating of the die bushing 2l). By employing the mandrel construction just described, any difference in coeiicient of expansion between the core member 24 and the die bushing 20 is'sufflciently compensated for by the rapid dissipation of heat resulting from the translation of air to positively prevent breakage of parts.

In Figure 3 a slightly modied mandrel construction is provided and in thisl connection particular attention is directed to the structure of the core member indicated by the numeral Zita. This core member 2da has a central passage 52a which communicates at'the right extremity with inclined radial passages lilla. These radial passages Mia communicate at their outer extremities with longitudinal passages 46a. which in turn communicate with companion radial ports or passages 48a. The right extremity of the core member 24a is reduced and threaded to receive a clamping nut 28a which functions similarly to the head 28 of the core member 2li in tightening the die bushing 20 in place. The translation or movement of air through the passages 42a, Ma,

' 46a and lla serves to effectively carry off excess heat from the die bushing 20 generated by the friction of the tube drawing mechanism.

Figure 4 discloses still another slightly modiiied core construction which comprises a core member 24h having a central longitudinal passage 12b which communicates at the right extremity with inclined radial passages Mb. These radial passages Mb communicate with companion longitudinal passages 36h and complementary or companion radial passages 48h. A solid head 28h is adapted to clampingly secure the die bushing 20 against longitudinal displacement. The movement of air through the above mentioned -passages into direct contact with the inner pesive temperatures, is completely obviated.

Obviously, the invention is not limited to the specific structural arrangement disclosed herein but is capable of other modifications and changes without departing from the spirit and scope of .the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, and an internal support element therefor, said parts having in association therewith passageways through which air may be moved into direct contact with said drawing member, whereby to maintain said drawing member within required working temperatures during the drawing operation.

2. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, and an interna] support element therefor, said parts having in association therewith longitudinally and radially disposed passageways through which cooling medium may be moved into direct contact with said drawing member and circulated externally about the same, whereby to maintain said drawing member within required working temperatures during the drawing operation.

3. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal tube drawing member, an internal support element therefor having a chamber for receiving a cooling medium in which a suicient portion of the inner periphery of said drawing member is exposed, and an exhaust passageway communicating with said chamber and the exterior of said drawing member to circulate the cooling medium externally about the tube drawing member, whereby to maintain said member within required working temperatures during the drawing operation.

4. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, a core member supporting said drawing member, a longitudinally extending chamber within said core member for receiving a cooling medium, a plurality of longitudinally extending chambers communicating with said rst chamber, a sufcient portion of the inner periphery of said tube drawing member being exposed within said last mentioned longitudinally extending chambers, and an exhaust passageway communicating with said last mentioned chambers and the exterior of said drawing member to circulate the cooling medium externally about the tube drawing member and internally of the tube being drawn, whereby to maintain said drawing member and the tube being drawn within required working temperatures during the drawing operation.

5. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, a core member supporting said drawing member, a longitudinally extending chamber within said core for receiving a cooling medium, a plurality of longitudinal chambers positioned externally of said first chamber, a plurality of radialchambers providing communication between said longitudinal chambers, a suicient portion of the internal periphery of said drawing member being exposed within said external longitudinal chambers, and a plurality of additional radial chambers providing communication between the external longitudinal chambers and the exterior of said core member to cause the cooling medium to circulate externally about the tube drawing member, whereby to maintain said drawing member within required working temperatures during the drawing operation whenair passes through said chambers.

6. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, a core member supporting said drawing member, a longitudinally extending air receiving chamber within said core member, a plurality of longitudinal chambers positioned externally of said rst chamber, a plurality of radial chambers providing communication between said longitudinal chambers, and peripherally disposed discharge openings communicating with said external longitudinal chambers and with the space between the core member and the tube being drawn,

a sufficient portion of the internal periphery of said drawing member being exposed within said external longitudinal chambers and a suilicient portion of the external periphery of said drawing member being exposed within the space between the core member and the tube being drawn, whereby to maintain said drawing member with- 'in required working temperatures during the vdrawing operation when air passes through said chambers and through the space between the core member and the tube being drawn.

'-7. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, an internal support element therefor, said parts having-,g in association therewith passageways through which air may be moved into direct contact with said drawing member, whereby to maintain said drawing member within required working temperatures during the drawing operation, and means for clampingly engaging said annular drawing member to secure said member in position upon said internal support element.

8. 'The method of drawing a tube which consis`ts in longitudinally passing said tube between the outer periphery of an internally supported non-ferrous, carbide-'type hard Ymetal tube drawing member and an externally supported nonferrous, carbide-type hard metal tube drawing member, and contemporaneously passing air longitudinally of and in direct contact with a sufcient portion of the inner periphery of the internally supported tube drawing member, whereby to maintain said internally supported drawing member within required working temperatures during the drawing operation.

9. The method of drawing a tube which consists in longitudinally passing said tube between the outer periphery of an internally supported non-ferrous, carbide-type hard metal tube drawing member and an externally supported nonierrous, carbide-type hard metal tube drawing 1 member, and contemporaneously passing a cooling medium longitudinally of and in direct contact with the entire length of a suflicient portion ,of the inner periphery of the internally supported tube drawing member and circulating said cooling medium about a suiiicien't portion of the external periphery of said internally supported tube drawing member, whereby to, maintain said internally supported drawing member within required working temperatures during the drawing operation.

10. In tube drawing apparatus, ra mandrel structure including` a non-ferrous, carbide-type hard metal annular tube drawing member, a hollow core member for receiving a cooling medium, said core member having a. clamping head for engaging one end of the tube drawing member, a sleeve encircling the core member forl clamping the tube drawing member against the clamping head of said core member, said core member having external openings in communication with its internal opening for circulating the cooling air internally of and in direct contact with the tube drawing member, said sleeve having an exhaust opening in communication with the external opening of the core member for circulating the cooling medium externally about a portion at least of the tube drawing member.

11. In tube drawing apparatus, a mandrel structure including a non-ferrous, carbide-type hard metal annular tube drawing member, and a supporting core for said tube drawing member, said core being spaced from the tube being drawn to provide an air circulating chamber therebetween and having an internal air receiving chamber in which a suiicient portion of the inner periphery of said drawing member is exposed, passageways providing communication between the internal air receiving chamber and the space between the core and the tube being drawn whereby to maintain the tube drawing member and the tube being drawn within required working temperatures during the working operation.

WALTER J. DENNIS. 

